The present invention relates to a structure and a method for mounting a heat-generating component on a circuit board accommodated in a space defined between a cover and a base so that heat generated by the heat-generating component is dissipated to the cover.
An electronic control unit for an industrial vehicle, for example, includes a heat-generating component such as a transistor mounted on a printed substrate in use for a circuit board accommodated in a casing. However, excessive heat generated by the heat-generating component is liable to cause the heat-generating component to incur a thermal destruction. To solve this problem, Japanese Patent Application Publication No. 2002-280776 discloses such a structure that heat generated by a heat-generating component is dissipated to a casing to suppress an excessive rise in temperature of the heat-generating component.
The structure for mounting a heat-generating element (or heat-generating component) disclosed in the above reference No. 2002-280776 includes a casing having therein a printed circuit board on which a heat-generating element is mounted and a heat-conductive sheet interposed between and in touch with the heat-generating element and the casing. Specifically, the heat-conductive sheet is pressed by the casing to be in contact with the heat-generating element so that heat generated by the heat-generating element is reliably transferred to the heat-conductive sheet and dissipated to the casing.
A structure for mounting a heat-generating element is generally arranged in such a way that a circuit board on which a heat-generating element is mounted is horizontally disposed in a casing and a heat-conductive sheet is provided above the surface of the heat-generating element, as disclosed in the reference No. 2002-280776. In this structure, the casing or the like presses the heat-conductive sheet from above against the heat-generating element so that the heat-conductive sheet and the heat-generating element are kept in contact with each other. On the other hand, there is known another structure for mounting a heat-generating element which is arranged in such a way that a circuit board is vertically disposed in a casing so as to extend in a sliding direction of a cover. In this case, the surface of the heat-generating element is substantially parallel to the sliding direction of the cover. Thus, the cover in sliding movement needs to press at the inner surface thereof the heat-conductive sheet against the heat-generating element. However, there is a problem with this structure in that the heat-conductive sheet is generally adhesive and, therefore, the heat-conductive sheet is adhered to and dragged by the sliding cover. As a result, the heat-conductive sheet is deformed or damaged and cannot be reliably pressed to contact with the surface of the heat-generating element. If the distance between the inner surface of the cover and the heat-conductive sheet is large enough to prevent the heat-conductive sheet from being dragged by the sliding cover, there arises another problem in that the heat-conductive sheet can not be sufficiently pressed to contact with the surface of the heat-generating element.
The present invention, which has been made in view of the above-described problems, is directed to a structure and a method for mounting a heat-generating component which prevent deformations of a heat-conductive member in sliding movement of the cover and ensures reliable pressing contact between the heat-conductive member and the surface of the heat-generating component.